Electronic devices generate heat during operation. Thermal management refers to the ability to keep temperature-sensitive elements in an electronic device within a prescribed operating temperature.
Historically, electronic devices have been cooled by natural convection. The cases or packaging of the devices included strategically located openings (e.g., slots) that allowed warm air to escape and cooler air to be drawn in.
The advent of high performance electronic devices, such as processors, now requires more innovative thermal management. Each increase in processing speed and power generally carries a “cost” of increased heat generation such that natural convection is no longer sufficient to provide proper thermal management. If the heat generated by such electronic devices is not removed at a sufficient rate, the devices may overheat, resulting in damage to the devices (e.g., diminished service life), and/or a reduction in operating performance of the devices.
One common method of cooling electronic devices includes thermally coupling a heat sink to the electronic device. A typical heat sink includes protrusions, such as fins or pins (commonly referred to as extended surfaces), which project from a body of the heat sink. The protrusions give the heat sink a larger surface area such that the heat sink dissipates a greater amount of thermal energy from the electronic device into the surrounding environment. Heat sinks are fabricated from materials with high thermal conductivity in order to efficiently transfer thermal energy from the electronic device to the ambient environment.
A fan is often used in conjunction with the heat sink to improve the heat sink's rate of cooling. The fan, which is typically mounted near the heat sink, causes  air to move past the fins on the heat sink. Moving air past the heat sink increases the rate of convection between the heat sink and the ambient environment where the heat sink is located. Increasing the rate of convection between the heat sink and the ambient environment reduces the temperature of the heat sink, thereby enhancing the heat sink's ability to transfer heat from the electronic device.
One drawback with conventional heat sinks is that when airflow is generated by a fan near the heat sink, the airflow is not efficiently utilized by the heat sink. Accordingly, there is a need for a heat sink that is able to make the most of the airflow generated by a fan near the heat sink in order to improve the rate cooling rate of the heat sink.